A Sand Martin photographed by Billy Clarke. The Sand Martin is a migratory bird in the swallow family. The food consists of small insects, mostly gnats and other flies whose early stages are aquatic. The Sand Martin is sociable in its nesting habits; from a dozen to many hundred pairs will nest close together, according to available space. The nests are at the end of tunnels of from a few inches to three or four feet in length, bored in sand or gravel. The actual nest is a litter of straw and feathers in a chamber at the end of the burrow. It lays 4 - 5 white eggs.